Conventionally, image recording/reproducing devices are used in various applications, such as recording of a surveillance camera image. An image recording/reproducing device concerned here is one with a hard disk as an image recording means.
Conventionally, in common image recording/reproducing devices, their hard disks are fixed-type and are permanently fixed in the equipment. Such image recording/reproducing devices have a hard disk failure detection function for maintenance purposes to replace a failed hard disk. Specifically, conventional image recording/reproducing devices determine that a disk failure has occurred and perform error handling when they lose recognition of a hard disk being in recording operation.
The case where a hard disk cannot be recognized is typically a case where no reply is received from a hard disk even when a Write or other command is executed on the hard disk. Such an error can be determined by using a timer. When a timeout occurs due to a command error during recording operation, error handling deals with the hard disk as a failed disk.
By the way, recently removable hard disks have been put to practical use that are different from the above conventional fixed-type hard disks. A removable hard disk is a hard disk that, being intended for removable use, employs a highly impact resistant and rugged cartridge. A removable hard disk can also be applied to an image recording/reproducing device. Such an image recording/reproducing device is disclosed in Japanese Patent Laid-Open Application No. 2005-123796, for example.
However, conventional image recording/reproducing devices have a problem that, when they are provided with a removable hard disk and if they perform conventional disk error detection simply as-is, they cannot discriminate between a disk failure error and a below-described disk separation error (disk-removed error) that is specific to removable hard disks. This problem will next be described in further detail.
An operation form of a removable hard disk will be considered here. At the start of operation of a removable hard disk, the removable hard disk is inserted into an image recording/reproducing device and then an operation start action is performed. The operation start action is an operator's button operation, for example. When the operation start action is performed, the removable hard disk is initiated and recognized, and then recording or other operation starts.
At the time of replacement or the like of the removable hard disk, an operation stop action is performed and then the removable hard disk is pulled out. The operation stop action is also an operator's button operation, for example. In response to the operation stop action, a process required to stop the operation is performed inside the equipment.
The above-mentioned operation stop action is performed in order to certainly keep an image to be recorded in the removable hard disk. When the operation stop action is performed, the image recording device performs on the hard disk a process corresponding to a shutdown. At this time, management information is written into a prescribed management area of the removable hard disk, for example. This allows the disk to be in a condition in which it can be pulled out. By performing the operation stop action, a partial loss of image or the like can be prevented.
However, in image recording devices that do not have a lock mechanism for preventing the removable hard disk from being pulled out, the removable hard disk can be pulled out by mistake or intentionally without the operation stop action. In that case, the image recording/reproducing device loses recognition of the removable hard disk and determines that a disk error has occurred. A disk error due to a removable hard disk being pulled out without going through a prescribed procedure as above will be called a disk separation error (disk-removed error).
A disk separation error is an error that does not occur in conventional fixed-type hard disks and is specific to removable hard disks. A disk separation error is also an error of a different type from a usually-detected disk failure error. However, these errors could not be discriminated by simply detecting a disk error depending only on whether a hard disk can be recognized or not as is conventionally done. Therefore, a user cannot be warned of disk separation. A user might determine by mistake that a hard disk is in failure.